1. Technical Field
This application relates to a system and method for the efficient and cost-effective storage and utilization of database information provided to a navigation device. In particular, this application relates to a system and method for the storage and utilization of geographic data for use in a GPS navigation device, in particular a vehicular GPS navigation device.
2. Related Art
Computer-based navigation systems are available that provide end-users (such as operators of vehicles, for example, automobiles, trucks, marine vehicles, airplanes, helicopters, and other types vehicles, in which the navigation systems have been installed) with various navigating functions and features. For example, some navigation systems may determine an optimum route of travel between two locations. In such a navigation system, a current position of a vehicle is detected by equipment that is capable of determining the vehicle's physical location, such as equipment utilizing a global positioning system (GPS). A navigation application program then may assess the various alternative routes between the two locations available to the operator and determine the optimum route. The system also may identify and provide the user with other information such as instructions for the route and the manoeuvres that may be required to execute the route. In one example of a navigational system, road map data and information relating to a road map data are obtained from a storage medium, for example, a compact disc or DVD mounted on the navigation device. The desired route from the current vehicle position to the desired destination point input by a user is determined, and the vehicle is guided from the current location along the determined route to the destination by using picture and voice.
Known navigation systems contain street data relating to the geometrical aspects of the street, for example, the position, the length, the geographical altitude, and the direction of the street. Using this street information data, a map can be built and presented on a display unit. Terms, present, presentation and presented are not limited to visual presentation, but are intended to encompass all means of presentation of data such as, for example, audio, visual, and combined audio and visual. The geometrical street data are normally stored as vectors indicating the length and the direction of the street. Various terminologies for describing the aspects of street information, and these other terminologies are intended to be encompassed within the scope of these concepts.
In addition to street information, navigation systems may comprise additional data containing location information. The location information data may include the name of the streets, classification of the streets, the type of street, for example a highway or a pedestrian zone, as well as other information. This location information data may also include information regarding hotels, gas stations, restaurants, landmarks, points of interest or any other information that may be helpful for the user of the navigation device.
Generally, navigation systems may receive and store the location information data together with the street information data, and thus, the data containing location information may be linked to the street data. If the data needed to present a certain region of a map is loaded into the data buffer of the navigation system, the whole data including street data together with a link to the other data containing location information is loaded. Where the data needed to present a certain region of a map is large, there may be insufficient space in the navigation system buffer to store and provide all of the street as well as the desired location information. Additionally, the storing of these data is highly complex and very time-consuming, requiring a large memory space to store the complete data.
Electronic travel guides are known in which additional location information data, for example, data of famous monuments, buildings, towns, or villages are stored on an electronic medium, such as a CD, together with their geographical position data. In known navigation systems, the information stored in these electronic travel guides may be loaded into the working memory of the navigation device and presented, for example, on a display of the navigation device. If, however, the navigation device is used to navigate the user to a certain destination, the whole working memory space may be filled with the map data needed to indicate the itinerary to the chosen destination. In such a situation, the user of the navigation device wants to have additional information from the electronic travel guide, this travel guide cannot be used simultaneously with the operating mode of the navigation device, for example, for navigating the vehicle. Thus, when the additional location information stored on the electronic storage medium of the travel guide is to be presented, this information of the electronic travel guide has to be loaded into the working memory of the navigation device and all or part of the information comprising the map data must be cleared from the working memory to make room for the location information. In conventional systems, switching between the two operation modes without clearing some of the memory in use for the navigation function is very difficult if not impossible. Therefore, there is a need for a navigation system which enables flexible presentation of street and location information.
Location information and street information typically are stored together in a single database. If a user desires updated location information, he may be required to purchase updated street information as well as the updated location information, thereby increasing his costs. Thus there is a need for a navigation system that enables cost-effective updates to the system.